Engine fuel supply having separate air and fuel mixing bores

ABSTRACT

A fuel supply system for an internal combustion engine, said system having a performance equal to that of a two-stage carburetor over a wide range of operation from small to large fuel requirements. The system has a first bore for regulating the inflow of air and a second parallel bore for mixing fuel with air. A throttle valve is provided in each bore and one of the throttle valves is connected to a fuel metering device. Metered fuel is injected into the fuel mixing bore at a Venturi that has a diameter considerably less than the diameter of the air inflow bore. In a second device, the fuel injection system controls fuel quantity by air jet pressure. In the last embodiment, the fuel metering device comprises pure fluid amplifiers which are controlled by pressure within the fuel and air mixing bore.

United States Patent [72] lnventors Junzo Uozumi;

Toshikazu Suzuki; Kaneo Kuno; Kazuo Klkuchi; Junki lwata, all of Aichi,,]apan [2]] Appl. No. 840,617 [22] Filed July 10, 1969 [451 Patented Sept. 28, 1971 [73] Assignee Aisan Kogyo Co., Ltd.

Alchl Prel., Japan [32] Priority July 18, 1968 [33] Japan 1'11 43/511687 I54] ENGINE FUEL SUPPLY HAVING SEPARATE AIR ANl) FUEL MIXING BORES 1 Claim, 4 Drawing Figs.

[52] U.S. Cl 261/28, 261/47,26l/1 16,261/1 17,261/D1G. 69, 261/69 R, 137/815 [5 l Int. Cl ..F02m 69/04 [50] Field of Search 261/46-48,

28,29, 36.1,D1G. 69,69 R, 69.1, 117, 116;

[56] References Cited UNITED STATES PATENTS 1,974,585 9/1934 Prentiss 261/28 2,223,381 12/1940 Mock 261/46 2,430,693 11/1947 7 Udale..... 261/23.1

Primary Examiner--Tim R. Miles At!0rney-Griffin, Branigan and Kindness ABSTRACT: A fuel supply system for an internal combustion engine, said system having a performance equal to that of a two-stage carburetor over a wide range of operation from small to large fuel requirements. The system has a first bore for regulating the inflow of air and a second parallel bore for mixing fuel with air. A throttle valve is provided in each bore and one of the throttle valves is connected to a fuel metering device. Metered fuel is injected into the fuel mixing bore at a Venturi that has a diameter considerably less than the diameter of the air inflow bore. In a second device, the fuel injection system controls fuel quantity by air jet pressure. In the last embodiment, the fuel metering device comprises pure fluid amplifiers which are controlled by pressure within the fuel and air mixing bore.

PAIENTED SEP2 8 1911 sum 1 nr 2 ENGINE FUEL SUPPLY HAVING SEPARATE AIR AND FUEL MIXING BORES PRIOR ART Carburetors heretofore known employ a single bore with means for injecting fuel into the bore upstream of a throttle valve. The bore downstream of the throttle valve is heated by the exhaust manifold of the engine to promote vaporization of fuel and to improve distribution of the fuel to each gas cylinder. Since a considerably volume of air must be heated in order to heat the fuel injected therein, the volume efficiency of this system is quite low.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fuel supply system having increased efficiency.

An object of the present invention is to provide a fuel supply system having a first bore for controlling the amount of air inflow and a second bore for mixing fuel and air, whereby the volume of air which must be heated to vaporize the field is considerably reduced.

An object of the invention is to provide a fuel supply system for an internal combustion engine, said system having first and second bores, a throttle valve in each of said bores, and fuelmetering means for injecting fuel into one of said bores upstream of the throttle valve therein. In one embodiment the fuel-metering means comprises a needle valve linked to one of the throttles. In a second embodiment the fuel-metering means comprises pure fluid amplifiers responsive to pressures within one of the bores for controlling the flow of fuel to said one bore.

A further object of the invention is to provide a fuel supply system having an air bore for regulating the inflow of air, a fuel bore for mixing fuel with air, a fuel pump, an air pump, means connected to the fuel pump for injecting fuel into the fuel bore, means connected to said air pump for injecting air into the fuel bore and against the fuel injected therein, and means for varying the rate at which the air or the fuel is injected into the fuel bore.

BRIEF EXPLANATION OF FIGS.

FIG. 1 is a longitudinal section of one of the invented carburetors;

FIG. 2 is a schematic representation of the fuel jet device of this invention;

FIG. 3(A) and (B) are longitudinal sections of the nozzle part of the device shown in FIG. 2; and,

FIG. 4 is a pipe arrangement of the invented carburetor with fluid amplifying elements.

DETAILED EXPLANATION OF THE INVENTION The invented devices are now explained by the use of Figures. In FIG. 1, (1) is the carburetor itself; (2) is the air system bore; (3) is the fuel systernbore; (4) is the main nozzle, (the fuel injection outlet) which opens at the Venturi (5); (6) is a float chamber; (7) is a float; (8) is a valve operated by the float to shut off or open the inlet (9) of the fuel; (10) is a metering jet; (II) is a metering needle for controlling the fuel flow from the main nozzle (4); (12) is an O-ring; (13) is a lever; (14) is a link; (15) is a throttle valve of the air system bore; (16) is a lever, one terminal of which is fixed on the rotating axle of the throttle valve (15) and the other terminal is connected to the lever (13) through the link (14). Since the lever (13) is connected to the metering needle (11), the throttle valve (15) willoperate in relation to the metering needle (II). (17) is a choke valve; (18) is an air vent; (19) is an adjusting screw for controlling the airflow during the engine idling. Instead of the screw as shown in the Figure, a pistonlike valve or a plate valve can also be used. During the engine idling, the throttle valve (15) of the air system bore is closed, but the quantity of fuel flow is determined by adjusting the metering jet (I0) or the metering needle (Ill). (20) is the throttle valve of the fuel system bore and is interlocked with the throttle valve of the air system bore mentioned above. During the engine idling, the throttle valve (I5) of the air system is completely closed and the throttle valve (20) of the fuel system is slightly opened to determine the quantity of air flow during the engine idling. When the fuel system throttle valve (20) is used for the determination of the quantity of air during the engine idling, the adjusting screw (I9) is not needed.

The size of the Venturi of the fuel system bore is slightly larger than that needed to maintain an adequate supply of fuel for the idling operation of the engine. The cross section of the Venturi has to be carefully determined so so that the liquid fuel can be converted to a fine mist. Our experimental results show that a 4-6 mm. Venturi system is suitable for an engine with l,000 to 2,000 cc. cylinders.

In the carburetor shown in FIG. I, the metering needle (11) and the throttle valve (15) of the air system are interlocked, but the metering needle can also be interlocked with the throttle valve (20) of the fuel system. In other words, the metering needle (11) is interlocked with at least one of the valves so that metering the required minimum fuel supply becomes possible.

The fuel injection device shown in FIG. 2 is cheaper and longer lasting than the conventional injection-type fuel supply device and is equipped with the invented air and fuel system bores; (21) is an air intake manifold; (22) is an exhaust manifold; (23) is a fuel tank; (24) is a fuel pump driven by the engine; (25) is a diaphragm valve operated by the suction pressure of the engine. During the full power output of the engine, its suction pressure is decreased and the diaphragm is opened. However, during the partial power output of the engine, the valve tends to close. In this way, the fuel supply is controlled. The fuel drawn out of the diaphragm valve (25) is supplied to the fuel injection nozzle (26) which opens into a fuel system bore (3). On the other hand, the air delivered by the air pump (28) is sprayed out from the nozzle (27), which opens at the opposite side of the nozzle (26), at a pressure slightly greater than the intake pressure. The kinetic energies of the fuel and the air sprayed out from their respective nozzles will collide, and the kinetic energy differential between the two is controlled by the air pressure P When I,, is greater than a certain value, the injection of fuel will be stopped. The quantity of the fuel injected will increase as P a is decreased. When I, is zero, the quantity of fuel injected will become maximum. According to this method, a. fine mist of fuel can be obtained when the quantity of fuel is small or the quantity of air is large. The quantity of air required can be varied also by a proper selection of the distance (d) between the two nozzles. By the same principle, the controlling method described in FIG. 3(B) can also be employed. In this Figure, (a) represents air and (1) represents fuel.

In FIG. 2, the air delivered from the air pump (28) is passed through a surge tank 29 for compensating the pulsation of pressure, the controlling valve (30), and the air-adjusting valve (31) for fuel control, and then sprayed out of the aforementioned nozzle (27). The quantity of fuel flow is controlled in the way mentioned above. The controlling valve (30) is a needle valve which in interlocked in such a way that its throt tling will change with the number of revolutions of the engine. When the number of revolutions is large, the needle valve is opened and the quantity of airflow tends to be throttled. The air-adjusting valve (31) is a diaphragm valve equipped with a operated by the suction vacuum of the engine. When the negative pressure is large, the valve will open completely; when the engaging pressure becomes small, the valve tends to be closed. Therefore, when the number of revolutions of the engine is increased by the action of the controlling valve (30) and the airadjusting valve (Bill), or when the suction vacuum is decreased by opening the throttle valve of the fuel system bore, the quantity of air injected will decrease. Consequently the quantity of fuel delivered from the fuel jet nozzle (26) will increase automatically and thus the quantity of fuel needed for the full power output of the engine is supplied.

FIG. 4 shows the use of a long lasting fluid-amplifying element containing no mechanically movable parts for the fuel supply to the fuel system bore (3). As indicated in the Figure, the fuel in the fuel tank (23) is delivered to the supply ports of the fluid-amplifying elements (100) and (200) by the use of the fuel pump (24). The fluid-amplifying elements (100), (200) and (300) are equipped with power output outlets (P and (P (P and (P,,), and (P and (P respectively, and also with control circuit terminals (C and (C (C and (C and (C and (C,,), respectively. The control circuit terminals (C (C,,) and (C are connected to the outlet (32), which opens at a part of the fuel system bore (3) and is used to take in the negative pressure used as a control signal. Therefore, each fluid-amplifying element is controlled by the intake vacuum of the fuel system bore. One side of the control circuit terminals (C of the fluid-amplifying element (300) is connected to the circuit switch (33). The circuit switch is interlocked with the throttle valve During the period of full power output in which the throttle valve (20) is opened wide, the circuit switch is opened to connect the control circuit terminals (C to atmospheric air, and the fluid-amplifying element (300) is now in a controllable state by the signal vacuum placed on the other side of the control circuit terminals (C When the engine is started, the fuel pump (24) shown in FIG. 4 starts to operate, and most of the fuel delivered to the fluid-amplifying element (100) is returned to the fuel tank (23) from the power output outlet (P During the idling operation, since the vacuum at the vacuum outlet (32) is very small, the control signal placed on the fluid-amplifying element (100) is also small. Consequently, only a small amount of fuel is supplied to the fuel system bore from the power output outlet (P via the nozzle (34). When the throttle valve (20) is opened further during the partial power output, more output fuel of the fluid-amplifying element (100) is shifted from the power output outlet (P to (P When the control signal vacuum is increased further, the fluid amplifying element (100) will be in a state of saturation and no more fuel can be supplied to the engine. The operation starting level of the fluid-amplifying element (200) is so predetermined that the element will start its controlling action when the control signal vacuum reaches the level slightly lower than that causing the saturation mentioned above. Therefore, during the partial power output of the engine, part of the fuel will be shifted from the power output outlet (P of the fluid-amplifying element (200) to the power output outlet (P as the intake vacuum increases and the fuel is then delivered to the bore (3) from the partial power output nozzle (35). The fuel output from the power output outlet (P is transferred to the supply port of the other fluid-amplifying element (300) and is returned to the fuel tank (23) via its power output outlet (P When the intake vacuum is increased further during the full power output of the engine, the circuit switch will be opened as mentioned before to start the operation of the fluid-amplifying element (300) and the fuel is shifted from the power output outlet (P to (P The fuel is now also supplied through the full power output nozzle (36). In the device shown in FIG. 4, the output fuel from each of the three fluid-amplifying elements (100), (200), and (300) is delivered to the engine successively and additively as the engine load is increased. In this way, a proper fuel supply can be maintained throughout the wide range of engine operation including the idling operation in which the fuel flow is small, and the full power operation in which maximum fuel flow is required. Since all of the fluid elements used share parts of the fuel supply to the engine, the accuracy of each fluid element does not have to be high to satisfy the required capacity. Therefore, a fuel system using the said fluid elements is cheap and will last longer.

Since the fuel system bore invented can be heated alone, the volume efficiency of fuel is improved and an increase in the power output of the engine can be expected. The improvement of power output and decrease in the quantity of incompletely burned gas can also be expected by promoting the fuel vaporization to improve the distributionof fuel to each cylinder. The improvement of power output can also be expected by decreasing the carburetor resistance because the size of the air system borecan be increased.

Since the Venturi diameter is decreased, the fuel flow speed is increased to promote the atomization of fuel, and the fuel distribution to each cylinder is improved. Therefore, the engine can reduce fuel consumption and effectively prevent air pollution. The engine can be operated with a gas mixture leaner than that provided by the conventional carburetor during alight engine load.

Since the quantity of fuel flow is made changeable by the air stream colliding with the fuel, a long lasting and less expensive fuel supply service can be obtained. The complicated and highly accurate fuel injection pump or the highly accurate injection nozzle required in the conventional injection system is no longer necessary in these invented devices.

Furthermore, since the fluid-amplifying element used in this invention can turn on mechanically movable part, the devices invented are long lasting and can be put to practical use as a device for controlling a wide range of fuel flow.

We claim:

1. In a fuel supply system for an internal combustion engine, the improvement comprising:

a first bore for regulating the inflow of air, said first bore forming a first airflow path along which operation of said internal combustion engine causes an airflow;

a second bore for mixing fuel with air, said second bore forming a second airflow path along which operation of said internal combustion engine causes an airflow said first and second bores merging into a single third bore at a merge zone located at downstream ends of said first and second bores;

a throttle means in at least one of said bores;

a fuel pump;

an air pump;

a fuel injection nozzle having an exit opening in said second bore;

an air injection nozzle having an exit opening in said second bore;

said exit openings being aligned whereby air and fuel exiting from said openings collide in said second airflow path of said second bore;

means responsive to said fuel pump for supplying fuel to said injection nozzle; and,

means responsive to said air pump for supplying air to said air injection nozzle including an air pressure-regulating means for regulating the pressure at which said air is supplied to said air injection nozzle and thereby regulating the fuel flowing from said injection nozzle exit opening. 

1. In a fuel supply system for an internal combustion engine, the iMprovement comprising: a first bore for regulating the inflow of air, said first bore forming a first airflow path along which operation of said internal combustion engine causes an airflow; a second bore for mixing fuel with air, said second bore forming a second airflow path along which operation of said internal combustion engine causes an airflow; said first and second bores merging into a single third bore at a merge zone located at downstream ends of said first and second bores; a throttle means in at least one of said bores; a fuel pump; an air pump; a fuel injection nozzle having an exit opening in said second bore; an air injection nozzle having an exit opening in said second bore; said exit openings being aligned whereby air and fuel exiting from said openings collide in said second airflow path of said second bore; means responsive to said fuel pump for supplying fuel to said injection nozzle; and, means responsive to said air pump for supplying air to said air injection nozzle including an air pressure-regulating means for regulating the pressure at which said air is supplied to said air injection nozzle and thereby regulating the fuel flowing from said fuel injection nozzle exit opening. 